Intrauterine Devices

An intrauterine device (IUD) is a small T-shaped plastic device that is placed in the uterus to prevent pregnancy. A plastic string is attached to the end to ensure correct placement and for removal. (An IUD should be removed only by a medical professional.)

Currently in the United States, 2 types of IUDs are available: copper and hormonal. Approximately 2% of women who use birth control in the United States currently use IUDs. The most recently introduced hormonal IUD is the levonorgestrel intrauterine system (LNG IUS or Mirena).

With a copper IUD, a small amount of copper is released into the uterus. This type of IUD does not affect ovulation or the menstrual cycle. Copper IUDs prevent sperm from being able to go into the egg by immobilizing the sperm on the way to the fallopian tubes. If an egg does become fertilized, implantation on the wall of the uterus is prevented because copper changes the lining of the uterus.

With hormonal IUDs, a small amount of progestin or a similar hormone is released into the uterus. These hormones thicken cervical mucus and make it difficult for sperm to enter the cervix. Hormonal IUDs also slow down the growth of the uterine lining, making it inhabitable for fertilized eggs.

The IUD is one of the most effective kinds of birth control available. According to the American College of Obstetricians and Gynecologists, only about 8 of 1,000 women who use the copper IUD will become pregnant in the first year of use. According to Planned Parenthood, fewer than 3 women out of 100 who use the progestin IUD become pregnant during the first year of use. The success rate with the LNG IUS system is even greater. With continued use, even fewer pregnancies occur. A woman can increase her protection by checking the IUD string regularly and talking with her doctor immediately if she notices a problem.

A woman using an IUD is always protected with nothing to remember. IUDs start working right away and can be removed at any time. IUDs are relatively inexpensive over time. The risk of side effects is low. IUDs can be inserted 6 weeks after the delivery of a baby or after an abortion. Women who use a copper IUD after childbirth can breastfeed safely. An IUD is not felt by a woman or her partner. Women who cannot use birth control pills because of cigarette smoking or conditions like hypertension may be able to use an IUD. Some women experience less menstrual blood loss and pain with hormonal IUDs.

The copper IUD can remain in place up to 10 years, while the LNG IUS is approved to protect women from pregnancy for up to 5 years when used in the United States and 7 years in Europe and Asia.

A doctor must insert and remove an IUD. Serious complications from IUD use are rare. IUDs come out during the first year of use in about 5% of women who use them. This is most likely to happen during the menstrual period. Women using IUDs should check their pads or tampons daily while menstruating and feel to make sure the string is in place regularly. If an IUD is expelled unnoticed, a woman may easily become pregnant. If pregnancy occurs while an IUD is still in place, the risk of miscarriage is 50% greater. This risk is decreased by 25% if the IUD is taken out as soon as possible. If the IUD is not removed, a risk of serious infection to the woman exists. Ectopic pregnancies in IUD users are half as likely as they are in women using no birth control. However, to reiterate, the risk of ectopic pregnancy is much less than itis in women who do not use any contraception. Women using IUDs who suspect they may be pregnant should contact their clinicians immediately.

An IUD may puncture the wall of the uterus when it is inserted. This occurs in 1-3 of 1,000 insertions. Cramping and backache may occur in the first few hours after an IUD is placed. Bleeding may occur for a couple of weeks after an IUD is placed. Some women have increased menstrual pain and heavy periods while using the copper IUD, but these symptoms are decreased in those using the hormonal IUD. Pelvic inflammatory disease is also possible with IUD use if a woman is not in a monogamous relationship and has an increased risk of STD transmission.

IUDs do not protect against STDs. STDs can be worse in women who have IUDs, and the chance of getting an STD may be higher in women who use IUDs during the first 4 months after they are placed. IUDs are best for women in relationships in which both partners are monogamous.